Among phenol type cyan couplers applied, for example, to a color photographic paper which is subjected to direct appreciation by human vision, the 2,5-diacylamino cyan coupler is well known in the art for its excellence in dark fading property. However the maximum absorption wave length of a dye formed from the above cyan coupler is found on the shorter wave side and the secondary absorption being large in the vicinity of 550 nm. Correspondingly, the dye formed from this reproducing cyan coupler has a disadvantage of not being capable of reproducing green color to a sufficient degree of brightness when compared to dyes formed from those conventional phenol type cyan couplers which do not have an acylamino group in the 5-position.
Furthermore, the phenol type cyan couplers with an alkyl group having more than two carbon atoms in the 5-position are well known among phenol type cyan couplers for having excellent color reproducibility. The dark fading property of a dye formed from such a cyan coupler, however, although better than conventional phenol type cyan couplers with a methyl group in the 5-position, has not yet reached a satisfactory level.
Japanese Patent Examined Publication No. 32727/1973, and Japanese Patent Publications Open to Public Inspection (hereinafter referred to as Japanese Patent O.P.I. Publications) Nos. 13923/1978, 119235/1979, 119921/1979, 119922/1979, 25057/1980, 36869/1980 and 81836/1981, respectively disclose a method of using a phosphoric ester compound as a high boiling organic solvent (HBS) into which a coupler is dissolved and dispersed, as a technique for improving hear/humidity resistance or dark fading property of a dye image formed from couplers.
In other words, additional improvement in image preservability of a cyan dye image formed from such a cyan coupler is possible if phosphoric ester compound is used together with either phenol type cyan coupler with an alkyl group having two or more carbon atoms in the 5-position or the 2,5-diacylamino cyan coupler mentioned above.
Nevertheless, through examination by the inventors, it was found out that the combined use of phosphoric ester compound and 2,5-diacylamino cyan coupler mentioned above, will not only cause the reduction in color density but also shorten the maximum absorption wave length and enhance secondary absorption in the vicinity of 550 nm as was mentioned above.
Furthermore, the secondary absorption is found in the vicinity of 420 nm in case if a dye formed from the 2,5-diacylamino cyan coupler or the phenol type cyan coupler with an alkyl group having more than two carbon atoms in the 5-position. While this secondary absorption is mostly insignificant in the absence of a phosphoric ester compound, the same compound, when employed together with the coupler, has a tendency to enhance the secondary absorption. The tendency is found to be particularly serious in the vicinity of 420 nm of a phenol type cyan coupler with an alkyl group having more than two carbon atoms in the 5-position.
In other words, while the combined use of a phosphoric ester compound and a 2,5-diacylamino cyan couplers enables an additional improvement in dark fading property, at the same time, it not only reduces the color forming property but also transfers the maximum absorption wave length to the short wave side, resulting in a considerable deterioration of color reproduction by reinforcing the large secondary absorption in the vicinity of 550 nm, a disadvantage of this particular coupler.
On the other hand, in case of a phenol type cyan coupler with an alkyl group having more than two carbon atoms in the 5-position, their minor weakness in dark fading property can be corrected by additional use of a phosphoric ester compound. Nevertheless, the use of the compound causes deterioration in color forming property as well as in color reproducibility due to a larger secondary absorption of the dye in the vicinity of 420 nm which otherwise does not occur.
As described so far, there has not been a silver halide photographic light-sensitive material containing a cyan coupler and featuring excellent dark fading, color reproduction as well as spectral absorption properties.
Through further examination as an attempt to fulfill the above-mentioned properties, the inventors have succeeded in obtaining a cyan dye image with adequate dark fading, color forming and spectral absorption properties, which consequently led to the present invention. The discovery of that particular cyan dye image has been made possible by emplying a specific phosphoric ester compound as well as a specific non-color forming compound together with at least a single cyan coupler selected out of a particular set of 2,5-diacyl cyan couplers or that of phenol series cyan couplers with an alkyl group having more than two carbon atoms in the 5-position.